1. Technical Field
The present invention relates to a robot control apparatus, a robot, and a robot system.
2. Related Art
Recently, in the field of robots, a force detector is used for controlling a motion position in response to a force applied to a manipulator. Here, the motion position refers to a position derived based on a target force in active impedance control and a force actually applied to the manipulator. Patent Document 1 (JP-A-2014-128857) discloses a technology that facilitates teaching by displaying temporal changes of the force applied to the manipulator and displaying temporal changes of the motion position of the manipulator.
Further, in the field of robots, force control of controlling the manipulator in response to the force applied to the manipulator is used. For example, FIG. 2 of Patent Document 2 (U.S. Pat. No. 7,340,323) shows a program for switching between a force control mode of controlling the manipulator in response to the force applied to the manipulator and a position control mode of controlling the manipulator regardless of the force applied to the manipulator using “Activate ForceControl;” command and “Deactivate ForceControl;” command.
Furthermore, in the field of robots, a technology of displaying a motion state of the robot on a display or a teaching pendant is known (see Patent Document 3 (JP-A-2007-196298) and Patent Document 4 (JP-A-2013-202731)). In Patent Documents 3, 4, the display and the teaching pendant are visually recognized, and thereby, the motion state of the robot may be recognized.
However, in the technology disclosed in Patent Document 1, a correspondence relationship between a target trajectory set for the robot and an actual motion trajectory is hard to understand. For example, it is necessary for a teacher to perform teaching while updating an initial position and a target position by trial and error in consideration of an actual motion trajectory relative to the target trajectory set for the robot, however, when the correspondence relationship between the target trajectory and the actual motion trajectory is hard to understand, there is a problem that a long time is required for determination as to whether or not the teaching is optimal.
Further, in the technology disclosed in Patent Document 2, when a command for operating the manipulator in response to the applied force is executed after switching from the position control mode to the force control mode by a command, there is a problem that reproducibility of the motion result of the manipulator is lower. That is, in the case where the crystal piezoelectric effect is used or the like, the outputs depends on time depending on the force detector, and the motion result differs depending on the time of the output of the force detector at which the manipulator is controlled. Specifically, when the force applied to the manipulator is detected with reference to the output of the force detector at the time of switching from the position control mode to the force control mode, the motion result differs due to differences in time after switching to the force control mode to execution of the command of actually operating the manipulator.
Furthermore, in the technologies disclosed in Patent Documents 3, 4, even when the motion state is displayed on the display and the teaching pendant, there is a problem that it is hard to intuitively recognize the displayed part of the robot in the motion state. Visual recognition of the display and the teaching pendant is required to confirm the motion state, and there is a problem that a user must look away once from the robot actually in motion.